Electric circuit breaker



Sept. 9, 1947. H. E. cox Er AL I ELECTRIC CIRCUIT BREAKER Filed June l, 1945 ,o vf 5mm We m f\-\!.\. J 3 mEwfm emA. 2 w o Hmm Til# Q :lfm b,

Patented Sept. 9, 1947 Webster. -1Wilcoxr.Hari-ow,l England; assignors'if to. General Electric: Company, a corporation oit-.-l

Application f J lnewl; 1945, Serial No.i 597,022; i In yGrieafe .Britain Octoberafw,` .19`44'-f' 1 Our invention relates:A to. 1electric=circuit break.v ersand more -particularly'to electric-circuit. brealfefl ersgpf. '.the fluicleorffgas` yblast Y type having sep-v arable' contacts between -which a blast of .-gas or iiuidL-is directed* for` yextinguishing:Y arcs@` -Speciii-,-` cally your y -inventionxis animprovement onaccpendingl ,.Boissexalu` .1 etV al. application Serial;v No.- 57.03006; `led Decemberffly' 194,4.,1r andl assigned to the same assignee as the present'applicationl In circuit breakersof thefkind referredtoabove it -is frequent practicefto providei-circuit.interruptimg. contacts .whichvfarefnormallyrheld in en gagement .by spring pressure and so-.- arranged'l that vwl-len: the breaker-is .toperfor-m an. openingy operationthe admission of@ air forother. fluid f une denn-pressure adjacent. Athe f,-.contactsffor intofthe chamber.A f surrounding .the contacts 'v causesf I them to.. open vbyY a .predetermined amount lallowing; -a uidiblast 11:0 owthrough suitable arcfextinguish'.

ingfnozzlesf.0 Infcircuit breakers of this `.typef-the supplytofruid to `the-arcing chamber effects both-- separa-tion of :the: contacts .landsA the.scavenging. of @the arcing -space :between stheseparatin-g con tacts: lWherethese circuit :breakers employ a ref tracting;rodtype contacta segmental finger-type'. sliding Acontact is generally required to-.carrythey current Y.to -,the`T movablecontact element. t This movablelfcontact-,is often `in .butt-engagement with f anassociated. i contact The' amount. of current which can be carried tley-)such butt-type'lcontacts of -a givenfmaterial, dependschieilyfuponthepressure exerted and. in. some `measureon ztheareaof. the..contact facesl.. Increase of the y.Contact area.` beyondaa certain amount ydoes not; .necessarily provider :..increased.. conductivity i because4 of the. practicable;impossibility A.of Jmaintaining. :con-tact overt-he'whole area and :it maybe saidthattheref is i a practical, `limi-t .to .current which..a cana-be. car.- riedeflicientlymy a.sing.1e.:pair otcontacts;`

It .is amebic-ect of ourcinventioni;to-.provide.a iluidblast circuit Abreaker with.acontactarrangea ment r.in .whichfthereis practically nolimit .to the.. current. ewhich.. can .be ..eicientlycarriedrfby the.

contacts.

It is. ,.another.. object. ,of..our. .invention to .proa

videY anew.. andsimproved electric .circuit interaY rupter. `in v.which the .Contact Astructure..comprises aplurality. `of pivotally mountedV- bladesor. sectors. normallyLurgedinto. engagemenawith a .cooper= ating. contact. ,t

It is .another .object. of .ourlinventiorn to .pro-

vide a new and improved gas blast circuit break-.

er in whichthelcontact-structure is readily rendered 'accessible on inspection... replacement ..or-

repairs.

2.115:` Further: -obj ects. and ad-Vantageslf-of. -iour inven. tion willabecomeeapparent astheffollowing,{deef scription =e proceeds; and' the1 features of @novelty whichf'characterize ourinventionz -Will 'bepointed out 'with'. particularityV` inthe claims -annexecl--to andiorminga part of this specification.

reference inlaybehadto the accompanyingdrawf ing-rinwhich-.Fig i :1 is: an 'felevationalf View partly" .i inisectionfof a -highfvoltage-Y electric circuitbreabern-embodying. the present invention-and.-.Fig-... 2 isa `sectional -iview 'takennonline-2 2 of--Fig.-1 assuming that-.Figa 1 .shows a complete vdevice withfno'parts cut aw'ayz Although our invention may be yapplied to Aa cir--l cuit` linterrupter A,having-fa single `set 1- of A arc= ex,

tingu-is'l-iing:y contacts; We fhave chosenlfto illustrate our invention as appliedxtoa circuit-interrupter comprising .two\- sets.of .'arcingontacts arranged in A s cries. 4so as '.to -fform 2 two .breaksin vseries generally-ireferredetoaseJ series multiple-break .gas blast -circuit breaker... AIt wilLbeunderstoodthat a .'polyphase?:circuitinterrupterswould employ an.

arrangement sucli.as'-issdisclosedfy inFig; 1 foreac-hphaseef the'circuit.-

I Referring nowfto-the drawing, the electric` circuit interrupter comprises an interrupting .unit generally indicateda at Which-is connected "in series"With-.anI .isolating-switch. y2 between'l circuit.

terminals 3 andu 4 of-an associated.circuitA toloeA controlled. .Y The interrupting uniti comprises an arcing chamber. .including an. upper chamber section-..5 dened-bya tubularmember yl of insulaty ing....materia1eand..a lower. chamber section?! de- 1 ned..by:-.a similar.- tubular member 8 .formed .of

insulating material... Ifdesired,.thetubulap meme..

bers r6 and..8-maybe enclosed-in -a weather resistant-.insulating. :materiallsuch as .porcelain,. or

preferablyAmay-fbe formed-of .aninsulating mae. terialWhich-in itselfis Weather: resistant.

The.. tubular: members. l vand -8v arearranged .in

axialY alinement Withthe member li arranged b'e-. lou/-the member/.16.. -Preferably..thefmember. 8 is arranged `in .sealingfengagement withfa suitable. yangem!! supportedon-a conducting=casting 4Ill Whiclrin turn.. may-.be supprtedona suitableY porcelain. insulator. or.V the'. --like.. :(not .shown-).--

Casting. Il) includesapassageway .I `I whereby fluid.

under: xpressure :may .be supplied .to chamber seca. tions.1 'and 5. Casting. .l0 alsofisprovidedwith a tubular. membenlZ which extendsintochamber. `.lv in .coaxial arrangement with -.loWer-. insulat ing member-t..` .Tubular-member vI 2 'is provided' with lanwannulancontact.surface .,l 3 surroundingr a central oriced 4 through-.which rfluictunder presa` sure may flow into tubular member I2 and thence out to atmosphere through a passageway I5.

In sealing engagement with the upper end of tubular insulating member 8 dening arcing chamber 1 is a flanged member IB provided with a hinge member I1. The lower end of tubular insulating member 6 is arranged in sealing enn gagement with a flanged member I8 similar to the flanged member I6 and provided with a cooperating hinge member I9 pivotally related to hinge member I1 by a pin 20. In normal operation of the circuit breaker the flanges IB and I 8 are united in sealed relationship by suitable fastening means, such as bolts 2 I, passing through the iianges thereof. However, access to the interior of each chamber section 5 and 1 through the ends of tubular members 6 and 8, which are adjoining, may be obtained by removing bolts 2l and pivoting the upper chamber 5 about pin 2D to the position shown in phantom in Fig. 1, or even further so that the adjoining ends of the chamber sections are in a horizontal plane.

In sealing engagement with the top of the upper tubular insulating member 6 is a flanged conducting member 22 electrically connected to line terminal 4. Flanged conducting member 22 supports a tubular conducting member 23 similar to tubular member I2 and arranged Within chamber section in coaxial relationship with tubular insulating member 6. Tubular member 23 terminates in an annular contact surface 24 surrounding an orifice 25 so that uid or gas under pressure may pass through orice 425, through tubular member 23 and thence to atmosphere. In order to prevent rain and snow from entering tubular member 23 we preferably provide a hood 26 supported from tubular member 23 by suitable means indicated at 21.

The tubular members I2 and 23 provided with annular contact surfaces I3 and 24, respectively, each comprise the stationary contact of the two sets of relatively separable contacts required in a gas blast breaker of the series multiple-break type. These annular contacts I3 and 24 are spaced apart along the axis of the arcing chamber so that one of these stationary contacts is disposed in each chamber section 5 and 1.

Interposed between stationary arcing contacts I3 and 24 is a unitary contact assembly generally indicated at 23 which might comprise a pair of retractable contacts one adapted to engage with each of the arcing contacts I3 and 24. As illustrated, the unitary contact assembly 28 comprises a unitary casting including a central cylindrical chamber member 29 symmetrically disposed about a pair of spaced plates 30 and 3l. The plates 30 and SI are of the same diameter as the flanges I 5 and I8 between which they are disposed, and are provided with a plurality of passageways 32 therethrough so that fluid under pressure may readily flow from chamber section 1 to chamber section 5. It will be observed that the spaced plates 30 and 3| serve as a flange which constitutes the sole support for the entire movable contact structure contained Within the interrupter so that by arranging this flange in clamping relationship between flanges I6 and I8 of the spaced chambers 1 and 5 as shown, the removal of the common clamping bolts 2l is all that is necessary for disconnecting the whole unitary movable Contact assembly 28 from the rest of the apparatus, thereby enabling a replacement unitary assembly to be substituted in short order.

Cylindrical chamber member 29 is disposed between and in axial alinement with tubular members I2 and 23 with the ends thereof spaced a predetermined distance from stationary annular contacts I3 and 24, respectively. The end of cylindrical chamber 29 adjacent annular contact I3 is provided with an orince 33 while the end of cylindrical chamber 29 adjacent annular contact 24 is provided with an orice 34. Cylindrica1 chamber 29 may function in the same manner as the arrangement disclosed and claimed in copending Wilcox application Serial No. 539,738, led June l0, 1944, and assigned to the same assignee as the present application. Fluid under pressure entering cylindrical chamber 29 through orifices 33 and 34 may escape to atmosphere through a plurality of openings 3-5 leading to horizontal passageways -36 between plates 3U and 3| interposed between the vertical passageways 32,

Radially disposed around the orifice 34 are a plurality of contact ngers 31, preferably pivotally mounted as is indicated at 38, to integral extensions 39 of cylindrical chamber member 29. Radially disposed movable contacts 31 are biased into engagement with annular contact 24 by virtue of spring means 40 arranged in any suitable manner, such for example, as the compression arrangement illustrated in Fig. 1. Identical radially disposed contacts are provided around orice 33 and these are'characterized by the same reference numerals.

For minimizing the expenditure of air or other extinguishing fluid flowing between the xed and movable contact structures from chambers 5 and 1, insert members 4I, which are shown as insulating sectors in Figs. 1 and 2, may be provided for blocking the intervening spaces between adjacent radially disposed contacts 31. Preferably, as indicated in Fig. 1, these insert members 4I are of the same thickness as the contacts 31 so that when the latter are pivoted to their fully opened position, in which position they lie horizontally seated against the disk-like surface surrounding the orices 33 and 34, the combined outer face of contacts 31 and insert members 4I constitutes a substantially unbroken plane disk like surface which is in spaced relationship from the adjacent disk-like surface of arcing contacts I3 and 24. This arrangement provides for a smooth streamlined inward radial flow between the separated contacts for the extinguishing fluid issuing from chambers 5 and 1.

In view of the above description, it will be clear that the contact structure of our invention may be regarded, in one aspect, as comprising two cooperating spaced disks between which an extinguishing fluid is caused to ow, portions of which disks constitute resilient conducting members for electrically bridging the gap therebetween. Heretofore, in comparable nozzle contact type interrupters, it has been conventional to cause separable movement of the whole cylindrical contact element, whereas, in accordance with our invention, only such portions of the nozzle contact structure as are essential for conducting current bridgingly across the nozzles are made movable, thereby reducing the mass of movable contact parts to a minimum. Hence, the smaller contact members open faster, renewals thereof are more economical, in addition to which better current transfer conditions across the separable contacts are afforded by virtue of providing more numerous positive points of contact.

In order to operate the circuit breaker embodying our invention fluid under pressure, such as air or other gas, is supplied to passageway II in.-.chamber sections 5 and-:1 presses.. movablel contacts 31. away 1. f romlthe stationary gannular. contacts .l3 aand* .2,4 to gdraw.. a; pluralty..,of arcs; between-.contacts;.3 and stationary.*annularcconev tants i3 and: 24.1? yrIhisffluid under pressure, passes4v aty high: 'veloci.ty. .throng-h.; orifices i214 3 3, f. 2 5 and 'r 34 therebyqrapidly extinguishing .the arcs-.which 1 are drawn-.1 @Therfiuidpassing .throughorices l 4 andgrows in `ithei..direction:'of the garrowsatof" atmospherepzas is shownfin Fig. 1.. .Theuid passe;

ine fthroughf orices L33 rand.. 34 :exhausts to .at-

mosph'ere-.through.openings-35 leading to 'atmos-z pherethrough .horizontal .passageways. 3 B between:- plates 3D and 3|, as is clearly indicatedby-fthe.;

arrows'in Figrl..

F01'. contributing .toward.holding.the contacts;

31 in..their fu1ly^openedeposition againstthe bias..= of' theinclosing springs, advantageiis taken v.01E the difference; '.in :fluidtypressurei pthat. jexistsz. between; theupstre'am. andI downstream-:regions.oni either;

sidefofithe `.orifices .33 andf34,..eand .whicnfdii'er-- enti'alziszknowmto'bevin.the ratioof about;2.'to v1.

Accordinglfwe: .provide a `suitableport or ports` 42 through-the end .walls'of the .cylindrical chaine". ber="29 iin `rWay .of .the innerzendfof each contact..

member:31,iand.whichrend walls 4provide conven-...r

ieni:v seating.'v surfaces .lforzestablishinga a limiting open.positionzforcontacts .31.-: One. suchxport. is clearly shown-throughffboth. the .upper anddower ends .of .chamber 29 ito .theJeft-rof and. adjacent tov the central" vorices 34 .iandw 33. vrespectively.,

Consequently, With 1, the contacts 31`pivoted 1to ..i their-limitinglopenhorizontal-position, thenhigh.L er .pressure .onf/heirfouter.faceseffectively:pree l ponderates rover-.the:lesserfrpressure at their. in-

ner facesdueltothe `presence of ports. 42 .which latter communicate `to .the-region. of 'lowerpres.- sure WithinA the Ycylindrical chamber. 29 'and which region exhausts 4.to atmosphere. viaithe v{openings 35 and-passageways 36.

Before..theow of air through-passagewayll 5- interrupted and'A radiallyldisposed .contacts `31 permittedto reclose.`

Whenit is desired'to close the circuit theisoe lating switch/2 alone may be operated,for ifV pre# f ferred'fluid under pressurejmay bedsupplied to ing "switch 2 whereupon radially disposedconblast is shutjoi.

It 'will 'be observed that the radiallyl disposedV contact flngers when in their lbilly-opened position; provide short are gaps ybetween' associated annular contacts.v I3 and 24, Whichjarc-gapsjj shouldl bejthe so-'called preferred gap/for morer satisfactory varc interruption.' along lthejliries ofKVA the arrangement v,disclosed and `claimedin co. pending Paul et al. application, Serial No'. 586,892; ledprl 6, 1.945,;and1assigned-to the samejas signee as the present application.

lthough in the preferred embodimentshown;A

both-the fixed and separablecontact structures are eachprovided with an orifice so that thefex- Y resilient contactarrangement of our invention'v will; function in :thersameadvantagious..manner` if. `butaa single-exhaust:passage;werefprovidede.

It will-.loe fobseryed-.thatywitn?the1hingedeconf.f struction ..:of-.Fig. 1 thea` unitary` .contacti assei'nbly.;v 28 containingalleof .theFmOVable partsof .thef-.n-:f

terrupting;unit.-.;l 1mm/abe readilyjfremoved. for inspection repaimor replacement..4

Whilegweihave shown;and.: described zafparticuf.; lan.embodiment.off jour. invention-5. it will be fobvi-z..` ous;l ato. those@ skiliedzrin l...theV art g thatgivarious y changes-:andimodicationsgmay ,zbe =made without; departing;..frompunginvcntiongin its;broader.,as'-.;.

clamscto zcover-.rallasuch echanges. zand modifican. tions ias .:fall-y Within.` the true :,spiritfandscopeqof our .invention;;r..

What .we1...claim.i;as1newgfandlzdesire; to "secureybyf LettersjRatentrof thellnited Statesyis rg.

1. In `fa uid';.blast;..electric circuit` breakencomf.. prising;.i1anf;arcing..'.chamberpa p1ura'lity,;.of .rela-` tivelyafseparable; contacts@y inm said. .pchamber=,1;.a.

sourcef/ofrruidzaunder@rpressura. meanswfor supe plyingffuidxaunden.pressurefrom. 'said-.source .to said arcing chamber, an orifice in one ofisadlr `relatively '.movablecontacts: through. .whichffluid under pressure supplied .to saidgchamberiexhausts..i therebyiprovidinga fluid. blast,.;the;other. of Said-.f contacts-.comprising.plural .conductingzmembersp disposedrradially; around :said milice, and.' means fomurginrgfssaid radially;disposed.:members inde-1. pendentlyinto;engagementwith said onecontactf.. saidlradiallyfdisposed membersrbeingarrangedto..A impedesthe iiiwiof. said: uidatowards .said ;orice g so ...that fthey are .mov.ed :..to disengaging.; position 3;.

Whenwsaifd 'udeis suppliedxto said. chamberifr..

2; `Inn fluid.y blastielectric .circuit breaker. come'. prism-gran.' arcing chambeigi a i plurality, 1 of .f relaff. i tivelyzi separablel contacts.V in .f saidv achamben; :a .i source .of Jrfiuid.. .runder-l2.:.press'ure,V means ,forxsupf plying fluid under-:pressure fromsaidfsOurcer'to.

re1atimaly:4 movable.contacts4 through/which :"uid. 1 undernpressure.'..supplied .to said chamber texas. hausts.thereby providing 1a fluid blastb :the-.other of vis'aidiicontracts: cor'nprising;.` plurali.:.cofiductingse` rnerifrbers-YV spaced vradiallyaroundLsaid oriice, andes spring-2v means ..1 for. vurging-1 said.. radially;.fspacecl4 members lindepende'ntly. into. r yengagement4 with: sai-d one (contactjsaid .membrsbeingzarranged to impede thellow-rfof said. .fluidiv towards *said orice f so :that :they .are -vmovedto disengaging. 4position when..said"fluid-is supplied .to-.said chamber; and.; means Lfor :blockingtheLintervening.l spaces. -dis:- posed between;saidplural; conducting '.membersr. 3 A1' fluidi blastaele'ctric. circuit breaker.. of :the 1 .1 series.'multiplex'breakltypef comprising.` a pressure.. chamber1 containing-groups .lof .radia-l'lyespaced. separable contacts .towhichf a supply. ofA pressure fluid is directed for effectingqbothgthe.separation4 f of'1thelconta'cts1 andfthe.scavengingcf' the arcing space :.:between-.fthe-. separated con'tactsf` wherein;v thejpressure chamber. is composed :of .at lea'sttwol cb amber? sections lhin-ged. together Iat adjoining ends-so that .the` one: sectioncontainingrvr at least l one ofthe contacts-.can be swungl .into 1a position Wherebyiithen-vto afford' iaccess .totheinterior of' each sectionwthrough. the .vends which 'were' *ade joined:

separablefcontacts lin said pressure; chamber; and a `source of .fluid :under pressure ffo'r supplying .a

blast .of riuidfadjai'centsaid. 'contacts' for aroextinguishi-ngfpurposesgfsaid ipressure chamber be"-`v f ingf composed ofA at leasty "twoy chamberseCtiOHs hinged together at adjoining ends so that the one section containing at least one of the contacts can be swung into a position whereby then to afford access to the interior of each section through the ends which were adjoined.

5. In a fluid blast electric circuit breaker of the series multiple-break type, an arcing chamber, a plurality of pairs of serially arranged relatively movable contacts in said chamber, means for supplying fluid under pressure to said chamber for effecting arc extinction upon separation of each of said pairs of relatively movable contacts disposed within said chamber, said pairs of contacts being disposed at different positions axially of said chamber so that said chamber comprises a plurality of chamber sections in each of which is accommodated one of said pairs of relatively movable contacts, means for hingedly connecting said chamber sections together in endto-end relation so that one section together with a contact contained therein can be swung into a position rendering accessible those parts within the sections which are nearest the adjoining ends thereof.

6. In a fluid blast electric circuit breaker, an arcing chamber, a pair of relatively movable contacts in said chamber, means for supplying fluid under pressure to said chamber for effecting arc extinction upon separation of said contacts disposed within said chamber, each of said contacts being disposed at a different position axially of said chamber so that said chamber comprises two chamber sections in each of which is accommodated one of said relatively movable contacts, and means for hingedly connecting said chamber sections together in end-to-end relation so that one section together with the contact contained therein can be swung into a position rendering accessible those parts within the sections which are nearest the adjoining ends thereof.

7. In a fluid blast electric circuit breaker, an arcing chamber, a pair of serially arranged relatively movable contacts in said chamber, means for supplying fluid under pressure to said chamber for effecting arc extinction upon separation of said relatively movable contacts disposed within said chamber, said chamber comprising a plurality of chamber sections with the contacts a1'- ranged to` engage each other at the junction between said chamber sections, and means for hingedly connecting said chamber sections together in end-to-end relation so that one section together with a contact contained therein can be swung into a position rendering accessible those parts within the sections which are nearest the adjoining ends thereof, one of said contacts being arranged in a unitary assembly so as to be readily withdrawn from one of said chamber sections for repair or replacement.

8. In a gas blast electric circuit breaker of the series multiple-break type comprising an arcing chamber, a plurality of relatively separable contacts in said chamber, said contacts being disposed at different positions axially of said chamber so that said chamber comprises a plurality of spaced chamber sections in each of which is accommodated a set of relatively separable ccntacts, a source of gas under pressure, means for supplying gas under pressure from said source to each of said arcing chamber sections, an orifice in one of each of said sets of relatively movable contacts through which gas under pressure supplied to each associated said chamber section may escape thereby providing a gas blast through each of said orifices, the others of said contacts of each set being disposed radially around said orifice, means for urging said radially disposed contacts into engagement with its associated contact containing said orifice, said radially disposed contacts being arranged to impede the flow of said fluid toward said orifices so that said contacts are moved to disengaging position for interrupting the circuit therethrough when said fluid is supplied to said chamber sections, a unitary contact assembly structure of which each said set of radially disposed contacts forms a part including a transverse supporting flange therefor, said flange constituting the spacing means separating said chamber sections, and means for securing said spaced chamber sections disconnectably to said flange whereby said unitary contact assembly is rendered readily replaceable.

9. In a fluid blast electric circuit breaker comprising an arcing chamber, a plurality of relatively separable contacts in said chamber, a source of fluid 'under pressure, means for supplying fluid under pressure from said source to said arcing chamber, an orifice in one of said relatively movable contacts through which fluid under pressure supplied to said chamber exhausts thereby providing a fluid blast, one of said contacts comprising plural conducting members dlsposed radially around said orifice, said radially disposed members being arranged yieldingly to impede the flow of gas toward said orifice so that they are moved to open circuit position when said fluid is supplied to said chamber.

l0. In a fluid blast electric circuit breaker comprising an arcing chamber, a source of fluid under pressure, means for supplying fluid under pressure from said source to said :arcing chamber, means defining an orifice in said chamber through which fluid under pressure supplied to said chamber may escape thereby providing a fluid blast, separable contact structure for producing an arc to be extinguished comprising a plurality of yieldable conducting members disposed radially about said orifice, means for biasing each said member individually to closed circuit position, and means for causing movement of each said member to open circuit position, said last mentioned means being responsive to pressure fluid supplied to said chamber.

11. A fluid blast electric circmt interrupter comprising a rst arcing chamber, a second arcing chamber arranged in spaced axial relationship with respect to said ilrst chamber, a fixed arcing contact mounted axially in each chamber at the end thereof adjacent the other chamber, a unitary contact assembly structure including two conductively connected independently movable contacts respectively `associated with said fixed contacts for drawing a series interrupting arc in each said chamber, means for biasing each said movable contact into engagement with its associated fixed contact, means for supplying gas under pressure to said first and second chambers, means responsive to fluid in each chamber for moving the associated movable contact out of engagement with the fixed contact therein, certain of said contacts being hollow for directing an yaxial blast therethrough, said unitary contact assembly including a transverse supporting flange constituting the spacing means for separating said first and second chambers one from another, and means for securing said first and second chambers disconnecta-bly to said flange whereby said unitary contact assembly is rendered readily removable and replaceable.

12. A fluid blast electric circuit interrupter comprising a first arcing chamber, a second arcing chamber arnanged in spaced axial relationship with respect to said first chamber, a fixed arcing contact mounted axially in each chamber at the end thereof adjacent the other chamber, a unitary contact assembly structure including two conductively connected independently movable contacts respectively associated with said fixed contacts for drawing a series interrupting arc in each said chamber, means for biasing each said movable contact into engagement with its associated xed Contact, means for supplying gas under pressure to said rst and second chamber, means responsive to uid in each chamber for moving the associated movable contact out of engagement with the fixed contact therein, certain of said contacts being hollow for directing an axial blast therethrough, said unitary contact assembly including a transverse supporting flange constituting the spacing means for separating said first and second chambers one from another, and means for clamping said flange between said rst and second chamber whereby said unitary contact assembly is rendered readily removable and replaceable.

13. In a fluid blast circuit interrupter, arcing contacts comprising two cooperating structures forming two substantially disk-like spaced surfaces having a preferred gap therebetween during circuit interruption, at least one of said structures including plural resilient conducting portions biased to bridge said gap electrically, and means for directing a blast of pressure fluid through said gap between said cooperating structures, said resilient portions being positioned in said gap so as to impede the flow of said fluid blast therethrough whereby they are moved by said fluid blast from their. biased position to circuit interrupting position, the impeding surfaces of said resilient conducting portions being constructed to form contributory parts of one of said disk-like surfaces when said resilient conducting portions are in the circuit interrupting position.

14. In a fluid blast circuit interrupter, arcing contacts comprising two cooperating structures :forming two substantially disk-like spaced surfaces having a preferred gap therebetween during circuit interruption, an orifice in one oi said structures forming a blast passage piercing one of said surfaces, at least one of said structures including plural resilient conducting portions arranged radially about said orifice and biased to bridge said gap electrically, and means for directing a blast of pressurey fluid between said cooperating structures and through said orifice, said resilient portions being positioned in said gap so as to impede the ow of said fluid blast therethrough whereby they are moved by said fluid blast from their biased position to circuit interrupting position, the impeding surfaces' of said resilient conducting portions being constructed to form contributory parts of one of said disk-like surfaces when said resilient conducting portions are in the circuit interrupting position.

15. In a fluid blast circuit breaker, an arcing chamber, relatively movable contacts disposed in said chamber for drawing an arc to be extinguished, one of said contacts being of the pivotal gate type biased to conducting engagement with another of said contacts, means for directing a blast of said pressure fluid between said contacts, said gate contact being positioned so as to impede the flow of said fluid blast whereby it is moved toward circuit open position by said fluid blast, means including a seating surface for establishing a limiting open position for said gate contact, and a port through said seating surface in way of said gate Contact and communicating to a region external to said chamber for producing a pressure differential which is effective to draw said contact toward and maintain it against said seating surface.

HAROLD ERNEST COX. THOMAS WEBSTER WILCOX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,982,355 Ruppel Nov. 2'?, 1934 2,287,039 Janssen June 23, 1942 2,160,673 Prince May 30, 1939 

